The central banks of this world, including our Federal Reserve, really do seem to want to engineer consistent growth and to keep the world economy humming, and in order to do so, they proceeded to take the unprecedented step of reducing interest rates, or the cost of borrowing money, well beyond historic lows, even going negative, over the last decade; but despite all of that tinkering in trying to reignite impressive GDP growth, this hasn't occurred for any of the European nations or for America, but rather the economic growth rate has instead been lukewarm, at best.
The theory behind low interest rates leading to accelerated economic growth is to a certain extent, just flipping the script from the theory behind high interest rates. That is to say, governments typically raise interest rates, and sometimes raise them very steeply, in order to slow an economy as well as the inflation rate down; because when the cost of money is very, very high, companies will reduce their investment in growth and expansion, and have a much stronger inclination to save up their money rather than to expend it; in addition, personal consumption will also be reduced, because people will save more of their money, for the interest rate return for parking one's money in savings or CDs is appreciably higher than normal.
This then implies, that super low interest rates, should expand business investment and economic growth, because the cost of doing business by borrowing money is appreciably lower, as well as people will spend more on consumption, because the interest rate for parking their money into savings, is so low. Although that is the theory, in effect, what really happens, is that, even though companies actually do borrow a lot more money when the cost of money is low, that money being borrowed isn't all being allocated to growth, though, part of it is, but rather a sizable percentage is instead, arbitraged or leveraged or invested into instruments that have a fairly high chance of making money, without a lot of appreciable risk. This means that public companies, will often borrow cheap money not so much to invest in their infrastructure, but rather to buy back their own stock, so as to increase their earnings per share, or raise dividends, and/or for mergers and acquisitions, because the borrowing of that cheap debt makes acquiring another company, appreciably cheaper.
This basically means, that the organizations and people that borrow money when interest rates are very, very low, are doing so, more often than not, in order to leverage up and to make relatively easy money, with minimal risk, of which that money so being made, is directed into primarily the hands of all those that already have sizable worth and assets to begin with; and unfortunately, those with the most sizeable assets don't overly expend money and don't make risky investment bets more than they need to, for they actually are both big savers as well as safe investors. So then, the result is that low interest rates, while being of some benefit for those that are in perpetual debt, like incompetent businesses and poorly compensated wage earners, doesn't do much for accelerating either growth or wages in aggregate, so that those that are paying less for that debt, aren't actually able to maneuver themselves out of that debt load, because they still don't have the income or means to do so.
So then, low interest rates, hurts retirees because they have no place to safely invest their money that doesn't involve some risk, and hence, get a very low return on their investment; it also doesn't benefit those that are barely scrapping by, for the economy is too quiescent, and hence there isn't any real wage growth; but it certainly does benefit those at the top of pyramid, providing them an easy tool, to make even more money, without a lot of risk, and this is exactly what they do.